Quick thought on reading the Shinkigami rules. It states you create one with an (artisan skill) check . Which makes sense, if you're making it from paper, it would be composition, if you're making a jewelry like piece, or sewing cloth or leather together, it would be design, ect.
But then it states that the invocations it casts use your Composition skill as its skill rank. Shouldn't that be the (artisan skill) it was created with? Composition if its paper, sure.